scholarly journals Coupled flight dynamics and CFD – demonstration for helicopters in shipborne environment

2017 ◽  
Vol 122 (1247) ◽  
pp. 42-82 ◽  
Author(s):  
C. Crozon ◽  
R. Steijl ◽  
G.N. Barakos
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Performance Studies ◽  
High Performance ◽  
Grid Method ◽  
Flight Mechanics ◽  
Helicopter Flight ◽  
Rotor Design ◽  
The Subject ◽  
Performance Computing

ABSTRACTThe development of high-performance computing and computational fluid dynamics methods have evolved to the point where it is possible to simulate complete helicopter configurations with good accuracy. Computational fluid dynamics methods have also been applied to problems such as rotor/fuselage and main/tail rotor interactions, performance studies in hover and forward flight, rotor design, and so on. The GOAHEAD project is a good example of a coordinated effort to validate computational fluid dynamics for complex helicopter configurations. Nevertheless, current efforts are limited to steady flight and focus mainly on expanding the edges of the flight envelope. The present work tackles the problem of simulating manoeuvring flight in a computational fluid dynamics environment by integrating a moving grid method and the helicopter flight mechanics solver with computational fluid dynamics. After a discussion of previous works carried out on the subject and a description of the methods used, validation of the computational fluid dynamics for ship airwake flow and rotorcraft flight at low advance ratio are presented. Finally, the results obtained for manoeuvring flight cases are presented and discussed.

scholarly journals A computational fluid dynamics simulation framework for ventricular catheter design optimization

2018 ◽  
Vol 129 (4) ◽  
pp. 1067-1077 ◽  
Author(s):  
Sofy H. Weisenberg ◽  
Stephanie C. TerMaath ◽  
Charlotte N. Barbier ◽  
Judith C. Hill ◽  
James A. Killeffer
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Standard Deviation ◽  
High Performance Computing ◽  
High Performance ◽  
Ventricular Catheter ◽  
Simulation Framework ◽  
Flow Rates ◽  
Catheter Design ◽  
Performance Computing

OBJECTIVECerebrospinal fluid (CSF) shunts are the primary treatment for patients suffering from hydrocephalus. While proven effective in symptom relief, these shunt systems are plagued by high failure rates and often require repeated revision surgeries to replace malfunctioning components. One of the leading causes of CSF shunt failure is obstruction of the ventricular catheter by aggregations of cells, proteins, blood clots, or fronds of choroid plexus that occlude the catheter’s small inlet holes or even the full internal catheter lumen. Such obstructions can disrupt CSF diversion out of the ventricular system or impede it entirely. Previous studies have suggested that altering the catheter’s fluid dynamics may help to reduce the likelihood of complete ventricular catheter failure caused by obstruction. However, systematic correlation between a ventricular catheter’s design parameters and its performance, specifically its likelihood to become occluded, still remains unknown. Therefore, an automated, open-source computational fluid dynamics (CFD) simulation framework was developed for use in the medical community to determine optimized ventricular catheter designs and to rapidly explore parameter influence for a given flow objective.METHODSThe computational framework was developed by coupling a 3D CFD solver and an iterative optimization algorithm and was implemented in a high-performance computing environment. The capabilities of the framework were demonstrated by computing an optimized ventricular catheter design that provides uniform flow rates through the catheter’s inlet holes, a common design objective in the literature. The baseline computational model was validated using 3D nuclear imaging to provide flow velocities at the inlet holes and through the catheter.RESULTSThe optimized catheter design achieved through use of the automated simulation framework improved significantly on previous attempts to reach a uniform inlet flow rate distribution using the standard catheter hole configuration as a baseline. While the standard ventricular catheter design featuring uniform inlet hole diameters and hole spacing has a standard deviation of 14.27% for the inlet flow rates, the optimized design has a standard deviation of 0.30%.CONCLUSIONSThis customizable framework, paired with high-performance computing, provides a rapid method of design testing to solve complex flow problems. While a relatively simplified ventricular catheter model was used to demonstrate the framework, the computational approach is applicable to any baseline catheter model, and it is easily adapted to optimize catheters for the unique needs of different patients as well as for other fluid-based medical devices.

scholarly journals Three-Dimensional Aerodynamic Analysis of a Darrieus Wind Turbine Blade Using Computational Fluid Dynamics and Lifting Line Theory

2017 ◽  
Author(s):  
Francesco Balduzzi ◽  
Alessandro Bianchini ◽  
Giovanni Ferrara ◽  
David Marten ◽  
George Pechlivanoglou ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Performance ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Cost Effective ◽  
Navier Stokes ◽  
Line Theory ◽  
Wake Model ◽  
Lifting Line

Due to the rapid progress in high-performance computing and the availability of increasingly large computational resources, Navier-Stokes computational fluid dynamics (CFD) now offers a cost-effective, versatile and accurate means to improve the understanding of the unsteady aerodynamics of Darrieus wind turbines and deliver more efficient designs. In particular, the possibility of determining a fully resolved flow field past the blades by means of CFD offers the opportunity to both further understand the physics underlying the turbine fluid dynamics and to use this knowledge to validate lower-order models, which can have a wider diffusion in the wind energy sector, particularly for industrial use, in the light of their lower computational burden. In this context, highly spatially and temporally refined time-dependent three-dimensional Navier-Stokes simulations were carried out using more than 16,000 processor cores per simulation on an IBM BG/Q cluster in order to investigate thoroughly the three-dimensional unsteady aerodynamics of a single blade in Darrieus-like motion. Particular attention was payed to tip losses, dynamic stall, and blade/wake interaction. CFD results are compared with those obtained with an open-source code based on the Lifting Line Free Vortex Wake Model (LLFVW). At present, this approach is the most refined method among the “lower-fidelity” models and, as the wake is explicitly resolved in contrast to BEM-based methods, LLFVW analyses provide three-dimensional flow solutions. Extended comparisons between the two approaches are presented and a critical analysis is carried out to identify the benefits and drawbacks of the two approaches.

scholarly journals Three-Dimensional Aerodynamic Analysis of a Darrieus Wind Turbine Blade Using Computational Fluid Dynamics and Lifting Line Theory

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Francesco Balduzzi ◽  
David Marten ◽  
Alessandro Bianchini ◽  
Jernej Drofelnik ◽  
Lorenzo Ferrari ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Performance ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Cost Effective ◽  
Navier Stokes ◽  
Line Theory ◽  
Wake Model ◽  
Lifting Line

Due to the rapid progress in high-performance computing and the availability of increasingly large computational resources, Navier–Stokes (NS) computational fluid dynamics (CFD) now offers a cost-effective, versatile, and accurate means to improve the understanding of the unsteady aerodynamics of Darrieus wind turbines and deliver more efficient designs. In particular, the possibility of determining a fully resolved flow field past the blades by means of CFD offers the opportunity to both further understand the physics underlying the turbine fluid dynamics and to use this knowledge to validate lower-order models, which can have a wider diffusion in the wind energy sector, particularly for industrial use, in the light of their lower computational burden. In this context, highly spatially and temporally refined time-dependent three-dimensional (3D) NS simulations were carried out using more than 16,000 processor cores per simulation on an IBM BG/Q cluster in order to investigate thoroughly the 3D unsteady aerodynamics of a single blade in Darrieus-like motion. Particular attention was paid to tip losses, dynamic stall, and blade/wake interaction. CFD results are compared with those obtained with an open-source code based on the lifting line free vortex wake model (LLFVW). At present, this approach is the most refined method among the “lower-fidelity” models, and as the wake is explicitly resolved in contrast to blade element momentum (BEM)-based methods, LLFVW analyses provide 3D flow solutions. Extended comparisons between the two approaches are presented and a critical analysis is carried out to identify the benefits and drawbacks of the two approaches.

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